Question

我有一个与其他实体电子邮件地址，电话有一对多关系的联系人实体。

这种关系（称为＆＃34;电子邮件，电话＆＃34;自然而然）也是有序的，这样我就可以在表格视图中显示联系人的电子邮件地址列表，并允许用户删除或修改每一个。据我所知，需要对它们进行排序，以便我可以判断哪一个被删除/修改：例如，如果用户点击第1行中的删除按钮，则应该从关系中删除第二个电子邮件地址。没有订购，我也不知道要删除哪一个。

生成NSManagedObject子类时，我在类上获得了一个NSOrderedSet属性，而CoreData在.h文件中提供了一些访问器：

@interface Contact (CoreDataGeneratedAccessors)
- (void)insertObject:(PLEmail *)value inEmailsAtIndex:(NSUInteger)idx;
- (void)removeObjectFromEmailsAtIndex:(NSUInteger)idx;
- (void)insertEmails:(NSArray<PLEmail *> *)value atIndexes:(NSIndexSet *)indexes;
- (void)removeEmailsAtIndexes:(NSIndexSet *)indexes;
- (void)replaceObjectInEmailsAtIndex:(NSUInteger)idx withObject:(PLEmail *)value;
- (void)replaceEmailsAtIndexes:(NSIndexSet *)indexes withEmails:(NSArray<PLEmail *> *)values;
- (void)addEmailsObject:(PLEmail *)value;
- (void)removeEmailsObject:(PLEmail *)value;
- (void)addEmails:(NSOrderedSet<PLEmail *> *)values;
- (void)removeEmails:(NSOrderedSet<PLEmail *> *)values;

- (void)insertObject:(PLTelephone *)value inTelephonesAtIndex:(NSUInteger)idx;
- (void)removeObjectFromTelephonesAtIndex:(NSUInteger)idx;
- (void)insertTelephones:(NSArray<PLTelephone *> *)value atIndexes:(NSIndexSet *)indexes;
- (void)removeTelephonesAtIndexes:(NSIndexSet *)indexes;
- (void)replaceObjectInTelephonesAtIndex:(NSUInteger)idx withObject:(PLTelephone *)value;
- (void)replaceTelephonesAtIndexes:(NSIndexSet *)indexes withTelephones:(NSArray<PLTelephone *> *)values;
- (void)addTelephonesObject:(PLTelephone *)value;
- (void)removeTelephonesObject:(PLTelephone *)value;
- (void)addTelephones:(NSOrderedSet<PLTelephone *> *)values;
- (void)removeTelephones:(NSOrderedSet<PLTelephone *> *)values;
@end

我的问题是，是否有任何方法可以使此代码通用，因此应删除isKindOfClass检查：

NSArray *nestedArray = [orderedSet array];
    id nestedObject = [nestedArray objectAtIndex:indexPath.row];
    if ([nestedObject isKindOfClass:[PLEmail class]]) {
        PLEmail *email = (PLEmail *)nestedObject;
        [email MR_deleteEntity];
        [self.contact removeEmailsObject:email];
    }
    else if ([nestedObject isKindOfClass:[PLTelephone class]]) {
        PLTelephone *telePhone = (PLTelephone *)nestedObject;
        [email MR_deleteEntity];
        [self.contact removeTelephonesObject:telePhone];
    }

Answer 1

如果您有互惠关系（按照建议），您可以在电子邮件或电话实体上取消联系关系。这也将从联系人列表中删除该实体。

处理多种关系的示例代码

- (void)removeRelationship:(NSString *)relationshipKeyPath fromEntity:(NSManagedObject *)entity {
    [entity setValue:nil forKeyPath:relationshipKeyPath];
}

你会像这样使用它：

[self removeRelationship:@"contact" fromEntity:unknownRelationshipForContact];

如何以某种通用方式删除有序到多个CoreData关系中的对象？

1 个答案: